A key function of coin dispensing hoppers (which are simply referred to as hoppers hereafter) is to extract single coins from a bulk of coins they retain within them, for example to dispense the coins from vending, gaming or change-giving machines. The prior art shows a variety of approaches to providing this coin extraction functionality. Many hoppers rely on a rotating, planar coin disk which, with the help of centrifugal forces, dispenses coins disposed on the coin disk from an outlet situated near the periphery of the coin disk. Examples of such prior art structures are discussed in greater detail below. An alternative approach involves the provision of a base plate and a rotating coin disk comprising several coin apertures. In such hopper structures, coins are generally held within the coin apertures of the coin disk, forced against a barrier by the movement of the coin disk and subsequently dispensed through peripheral openings in the coin disk. An example of a hopper that utilises a coin disk comprising coin apertures is described in UK Patent Application GB 2352862.
It is commonly known to load more than one denomination and/or value of coin into a single hopper. Hoppers that are capable of dispensing coins having a variety of shapes and sizes, referred to as universal hoppers herein, are advantageous since they allow vending machines to function with only a single hopper, saving manufacturing costs, hopper maintenance costs and space. It will be appreciated that vending machines comprising a universal hopper generally include means of identifying and sorting as appropriate the different kinds of coins dispensed from the hopper. Specifically, when different types of coins are present in a hopper, selection of a desired type of coin is achieved by extracting a single coin at a time, determining its type/value and then either accepting it if it is the desired value or recirculating it back into the hopper if it is not. Much prior art exists teaching different mechanisms for achieving sorting and identification, see U.S. Pat. No. 4,036,242 for example.
Although universal hoppers have great advantages, particularly since identifying and sorting extracted coins is an area of technology that is well evolved, they also have inherent difficulties associated with them.
The internal mechanisms of a universal hopper must be configured to dispense individually, quickly and reliably coins having a variety of diameters, thicknesses, and sometimes even shapes (not all coins are strictly discoid—they may, for example, also be hexagonal, heptagonal or octagonal). One of the biggest challenges that must be overcome is the specific requirement for coins to be dispensed individually which arises, for example, because most coin sorting and identifying mechanisms, i.e. the mechanisms generally located immediately downstream of a universal hopper, only work reliably when supplied with a stream of individual (single) coins. A key problem that is well documented in the prior art is that where a hopper's internal coin extraction mechanism is set up to extract coins of a comparatively greater thickness it is possible for two coins of a comparatively lower thickness to stack on top of each other to be dispensed in combination (i.e. not individually, as required) because they mimic the shape of a single thicker coin.
A great deal of prior art attempts to deal with the problem of stacks of two or more thinner coins mimicking a thicker coin in universal hoppers (hereinafter referred to as “the double coin problem”). However, it has been found that the double coin problem generally forces a compromise having to be struck between (i) the variety of coins that can be processed in a given hopper and (ii) the mechanical complexity, and hence associated cost and reliability, of the internal parts of the hopper. Universal hoppers that support a great variety of coin diameters, thicknesses and shapes generally require a large number of complex parts, particularly to deal with the double coin problem, and are thus expensive, whilst hoppers that have a simple, reliable and cost effective structure are generally limited to either a single dimension of coins or a very narrow range of coin sizes and shapes.
To show how the prior art has attempted to solve the double coin problem, and to illustrate that prior to the present invention there has been a trade-off between mechanical complexity and scope of coin support, a number of prior publications will now be discussed.
European Patent Publication EP 0017610 describes a device for separating single coins from a bulk of coins comprising thick coins of a large diameter and thin coins of a small diameter. The device is of the rotatable planar disk type discussed above. A first spring biased coin stripping arm is mounted above the coin disk at a height which allows the thick coins to pass underneath the first arm (when the coins are supported in a horizontal position on the coin disk) but prevents the passage stacks of two or more thick coins or the combination of a thick coin and a thin coin. When stacks comprising at least one thick coin come into contact with the leading edge of the first coin stripping arm, only the lowermost coin is allowed to pass underneath the arm, whilst upper coins are stripped off the lowermost coin and return to the coin disk to attempt a further pass of the first stripping arm.
It will be appreciated that when the device of EP 0017610 is loaded with thin coins having a thickness which is less than half that of the thick coins, it is possible for stacks of two or more thin coins to pass underneath, and thus downstream of, the first stripping arm. To prevent such stacks of comparatively thinner coins from being dispensed via its exit conveyor belt, the apparatus of EP 0017610 comprises a second coin stripping arm mounted above the coin disk, downstream of the first stripping arm. The second coin stripping arm is formed by two spring-biased arm parts having shapes that are specifically adapted to recognise the diameter of approaching coins: the second coin arm is caused to lift and allow the passage of thick, large diameter coins but not of stacks of small diameter coins. Thus the apparatus of EP 0017610 is capable of preventing the passage of stacks of thin coins on to its exit conveyer belt based on the assumption that thin coins have a smaller diameter than thick coins.
Clearly, EP 0017610 only offers a very limited solution to the double coin problem. The device of EP 0017610 must be configured precisely to correspond to the dimensions of the coins that are to be processed. Configuration applies not only to the respective heights of the first and second stripping arms but also to the specific length and shape of the various parts of the second stripping arm. Additionally, the solution of EP 0017610 is only applicable where thinner coins indeed have a smaller diameter than thicker coins, which is not given in many monetary systems around the world.
It is clear that, although EP 0017610 does support a limited amount of variation in coin dimensions, it does not completely fulfil needs in this respect. Nevertheless, what little flexibility EP 0017610 offers in terms of coin dimensions comes at a heavy price in the context of complexity of design. The device of EP 0017610 comprises a large number of small components and the structure of the second stripping arm in particular is complicated and sensitive. This in turn means that the device of EP 0017610 is expensive to manufacture and maintain and likely to be relatively vulnerable to faults and wear and tear.
A second solution proposed by the prior art is disclosed in DE 333 0441. Again, a planar coin disk structure configured for a two stage process of stripping to prevent the passage of coin stacks is envisaged. A first, rigid stripping arm performs an initial stripping function which is augmented by a second coin stripping arm downstream. The second coin stripping arm is formed as a row of balls which are resiliently mounted close above the coin disk. The balls are mounted at a height just greater than the thickness of the thinnest coins processed by the device and are deflected upwards by any passing single thick coins, in use, whilst stripping any stacks of coins that pass the first stripping arm.
The arrangement of DE 333 0441 is more versatile than that of EP 0017610 in that it does not rely on the premise that thick coins have a larger diameter than thin coins. Nevertheless, it requires painstaking calibration of the first and second stripping arms to take into account the specific dimensions of the range of coins that is processed. The distance between the balls, for instance, is dependent on the diameter of the processed coins. It will be appreciated that the need for calibration in turn has an effect on the level of maintenance required; faults are more likely to occur, particularly since margins are fine and moving parts are involved. There is also potential for coins to get wedged under the non-biased first stripping arm. Further, the row of balls acting as the second stripping arm in particular is expensive to manufacture and replace (as would be necessary if the diameter of processed coins were to vary). In summary, whilst DE 333 0441 supports a greater variation in coin dimensions, it is possibly even harder to maintain, configure and manufacture, largely as a result of the row of balls.
A further prior art system, again having a planar coin plate structure is disclosed in U.S. Pat. No. 4,657,035. Here a second stripping system comprising a narrow stripping arm and a conveyor belt is employed downstream of a first coin stripper. The narrow stripping arm diverts the lowermost coin in any stack towards the coin exit of the device whilst the conveyer belt acts to force any superposed coins away from the exit, thus stripping them away.
The provision of a conveyer belt to disrupt any stacks of coins that progress past the first coin stripper of U.S. Pat. No. 4,657,035 provides a solution to the problem of double coins irrespective of coin diameter. However, once again, careful calibration of the entire device is necessary in response to the specific size of the coins that are to be processed. Additionally, the second stripping system, although flexible in terms of the dimensions of input coins is mechanically complex since it requires a drive mechanism and belt. This mechanical complexity, coupled with the need for precise calibration makes the device of U.S. Pat. No. 4,657,035 particularly susceptible to faults and expensive to maintain and produce. The complexity of the device of U.S. Pat. No. 4,657,035 is increased further by the fact that the relatively simple structure of the narrow stripping arm itself leads to the need for an additional closing element that stops small diameter coins from being dispensed in the slip stream of larger coins.
In summary, the prior art does not disclose a truly satisfactory (i.e. simple, effective and reliable) solution to the double coin problem. Prior art devices are all either inflexible in their intake of coins or highly complex, or both. Furthermore, most prior art devices must be carefully configured to match the coins that they are to process, which in turn leads to high maintenance costs and greater fault vulnerability. Finally it is noted that the vast majority of prior art solutions for the double coin problem are only suitable for use in planar coin disk type hoppers. Thus hoppers that rely on a coin disk with apertures cannot at present be equipped with a system that would allow them to function effectively as universal hoppers, which are required to dispense a wide variety of coins individually. The prior art solutions to the double coin problem require too much space in order to work effectively in combination with a hopper relying on a coin disk with coin apertures.
It is an object of the invention to overcome at least one of the problems associated with prior art hoppers or coin dispensing mechanisms.